Wireless communication device and power receiving unit with wireless control channel and methods for use therewith

ABSTRACT

Aspects of the subject disclosure may include, for example, a power receiving unit having a wireless power receiver that receives a wireless power signal from a power transmitting unit. A rectifier circuit rectifies the wireless power signal to generate a rectified power signal in response thereto for charging a battery. A first wireless radio unit exchanges control data with a second wireless radio unit of the power transmitting unit via a wireless control channel, wherein the exchange of control data facilitates establishment of the wireless control channel, establishment of a charging session between the power receiving unit and the power transmitting unit, and control of the charging session between the power receiving unit and the power transmitting unit.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present U.S. Utility Patent Application claims priority pursuant to35 U.S.C. § 120 as a continuation of U.S. Utility application Ser. No.15/835,999, entitled “WIRELESS COMMUNICATION DEVICE AND POWER RECEIVINGUNIT WITH SWITCHING PREDICTION AND METHODS FOR USE THEREWITH”, filedDec. 8, 2017, which claims priority pursuant to 35 U.S.C. § 120 as acontinuation of U.S. Utility application Ser. No. 14/954,095, entitled“WIRELESS COMMUNICATION DEVICE AND POWER RECEIVING UNIT WITH SWITCHINGPREDICTION AND METHODS FOR USE THEREWITH”, filed Nov. 30, 2015, whichclaims priority pursuant to 35 U.S.C. § 119(e) to U.S. ProvisionalApplication No. 62/248,778, entitled, “WIRELESS COMMUNICATION DEVICE ANDPOWER RECEIVING UNIT WITH SWITCHING PREDICTION AND METHODS FOR USETHEREWITH,” filed Oct. 30, 2015, all of which are hereby incorporatedherein by reference in their entirety and made part of the present U.S.Utility Patent Application for all purposes.

BACKGROUND Technical Field

Various embodiments relate generally to wireless communication systems,wireless power systems, and also to wireless charging of devices.

Description of Related Art

Communication systems are known to support wireless and wirelinecommunications between wireless and/or wireline communication devices.Such communication systems range from national and/or internationalcellular telephone systems to the Internet to point-to-point in-homewireless networks. Each type of communication system is constructed, andhence operates, in accordance with one or more communication standards.For instance, wireless communication systems may operate in accordancewith one or more standards including, but not limited to, IEEE 802.11,Bluetooth, Bluetooth Low Energy (BLE), advanced mobile phone services(AMPS), digital AMPS, global system for mobile communications (GSM),code division multiple access (CDMA), local multi-point distributionsystems (LMDS), multi-channel-multi-point distribution systems (MMDS),and/or variations thereof.

The Alliance for Wireless Power (A4WP) has promulgated a baselinesystems specification for interoperability of loosely coupled wirelesspower transfer for portable, handheld electronic devices. Thisspecification supports a 6.78 MHz for power transfers and a 2.4 GHzoperating frequency for management data transfers. The Wireless PowerConsortium (WPC) has also promulgated standards used for wirelesscharging of mobile devices, notably the Qi low power specification.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a schematic block diagram of an embodiment of a wirelesscommunication device;

FIG. 2 is a schematic block diagram of an embodiment of components of awireless charging system;

FIG. 3 is a graphical diagram of embodiments of switching waveforms;

FIG. 4 is a schematic block diagram of an embodiment of components of awireless charging system;

FIG. 5 is a graphical diagram of an embodiment of switching waveforms;

FIG. 6 is a schematic block diagram of an embodiment of components of arectifier control circuit and a rectifier circuit;

FIG. 7 is schematic block diagrams of embodiments of adjustable voltagegenerators;

FIG. 8 is a schematic block diagram of an embodiment of a powertransmitting unit and a wireless charging circuit;

FIG. 9 is a flowchart representation of an embodiment of a method; and

FIG. 10 is a flowchart representation of an embodiment of a method.

DETAILED DESCRIPTION

FIG. 1 is a schematic block diagram of an embodiment of a wirelesscommunication device. A wireless communication device 100 is shown suchas a 2G, 3G, or 4G/LTE smartphone capable of making and receivingwireless phone calls, and transmitting and receiving data using 802.11a/b/g/n/ac/ad (“WiFi”), Bluetooth (BT), Near Field Communications (NFC),or any other type of wireless technology. In addition to making andreceiving phone calls and transceiving data, the wireless communicationdevice 100 optionally runs any number or type of applications. Thewireless communication device 100 may draw energy from numerousdifferent sources. As one example, the wireless communication device 100may draw energy from the battery 101. Other sources of energy includeWireless Power Transfer (WPT) energy sources. In that respect, describedfurther below are techniques for harvesting power from wireless signals.

The wireless communication device 100 is shown as a smartphone in thisexample, but the functions and features described herein can likewise beimplemented in other host devices such as a laptop, tablet, cellphone, aperipheral host device such as a keyboard, a mouse, a printer, amicrophone, headset, headphones, speakers or other peripheral, a driverassistance module in a vehicle or other vehicle based device, anemergency transponder, a pager, a watch including a smart watch, asatellite television receiver, a stereo receiver, music player, homeappliance and/or any electronic host device that compatible withwireless charging or other wireless power transfer.

In the embodiment shown, the wireless communication device 100communicates with a network controller 150, such as an enhanced Node B(eNB) or other base station. The network controller 150 and wirelesscommunication device 100 establish communication channels such as thecontrol channel 152 and the data channel 154, and exchange data. Thewireless communication device 100 may be exposed to many other sourcesof wireless signals as well, e.g., from a wireless power transmittingunit 156, and wireless signals may be harvested in conjunction with theWPT techniques described herein.

In the embodiment shown, the wireless communication device 100 supportsone or more Subscriber Identity Modules (SIMs), such as the SIM1 102 andthe SIM2 104. Electrical and physical interfaces 106 and 108 connectSIM1 102 and SIM2 104 to the rest of the user equipment hardware, forexample, through the system bus 110.

The wireless communication device 100 includes communication interfaces112, system logic 114, and a user interface 118. The system logic 114may include any combination of hardware, software, firmware, or otherlogic. The system logic 114 may be implemented, for example, with one ormore systems on a chip (SoC), application specific integrated circuits(ASIC), discrete analog and digital circuits, and other circuitry. Thesystem logic 114 is part of the implementation of any desiredfunctionality in the wireless communication device 100.

The system logic 114 may further facilitate, as examples, decoding andplaying music and video, e.g., MP3, MP4, MPEG, AVI, FLAC, AC3, or WAVdecoding and playback; running applications; accepting user inputs;saving and retrieving application data; establishing, maintaining, andterminating cellular phone calls or data connections for, as oneexample, Internet connectivity; establishing, maintaining, andterminating wireless network connections, Bluetooth connections, orother connections; and displaying relevant information on the userinterface 118. The user interface 118 and the inputs 128 may include agraphical user interface (GUI), touch sensitive display, voice or facialrecognition inputs, buttons, switches, speakers and other user interfaceelements. Additional examples of the inputs 128 include microphones,video and still image cameras, temperature sensors, vibration sensors,rotation and orientation sensors, headset and microphone input/outputjacks, Universal Serial Bus (USB) connectors, memory card slots,radiation sensors (e.g., IR sensors and/or other sensors), and othertypes of inputs.

The system logic 114 may include one or more processors 116 and memories120. The memory 120 stores, for example, control instructions 122 thatthe processor 116 executes to carry out desired functionality for thewireless communication device 100. The control parameters 124 provideand specify configuration and operating options for the controlinstructions 122. The memory 120 may also store any BT, WiFi, 3G, orother data 126 that the wireless communication device 100 will send, orhas received, through the communication interfaces 112. The wirelesscommunication device 100 may include a power management unit integratedcircuit (PMUIC) 134. In a complex device like a smartphone, the PMUIC134 may be responsible for generating, e.g., thirty (30) different powersupply rails 136 for the circuitry in the wireless communication device100.

In the communication interfaces 112, Radio Frequency (RF) transmit (Tx)and receive (Rx) circuitry 130 handles transmission and reception ofsignals through one or more antennas 132. The communication interface112 may include one or more transceivers. The transceivers may bewireless transceivers that include modulation/demodulation circuitry,digital to analog converters (DACs), shaping tables, analog to digitalconverters (ADCs), filters, waveform shapers, filters, pre-amplifiers,power amplifiers and/or other logic for transmitting and receivingthrough one or more antennas, or (for some devices) through a physical(e.g., wireline) medium.

As just one of many possible implementation examples, the wirelesscommunication device 100 may include (e.g., for the communicationinterface 112, system logic 114, and other circuitry) a BCM59351charging circuit, BCM2091 EDGE/HSPA Multi-Mode, Multi-Band CellularTransceiver and a BCM59056 advanced power management unit (PMU),controlled by a BCM28150 HSPA+ system-on-a-chip (SoC) basebandsmartphone processer or a BCM25331 Athena™ baseband processor. Thesedevices or other similar system solutions may be extended as describedbelow to provide the additional functionality described below. Theseintegrated circuits, as well as other hardware and softwareimplementation options for the wireless communication device 100, areavailable from Broadcom Corporation of Irvine Calif.

The power transmitting unit 156 or another power source may generate awireless power input signal. A controllable rectifier circuit 160receives the wireless power input signal via a wireless power receiver158. The output of the controllable rectifier circuit 160 is thewireless power output signal 162, Vrect, that can be used by chargingcircuit 164 to charge a battery 101 of the wireless communication device100 and/or to provide other system power.

In various embodiments, the controllable rectifier circuit includes arectifier having a switching circuits configured to generate a rectifiedvoltage, Vrect, from the wireless power signal, based on switch controlsignals that include a switch-on signal and a switch-off signal for eachswitching circuit. A rectifier control circuit generates the switchcontrol signals based on predicted switching delays. In addition, thesystem logic 114 may exercise control over controllable rectifiercircuit. In particular, one or more processors 116 can execute controlinstructions 122 to change switching prediction parameters that affectthe switch timing of the controllable rectifier circuit 160. Inaddition, the memory 120 may also store nominal control parameters 166.The nominal control parameters 166 may set or alter switching timing forthe controllable rectifier circuit 160 for pre-defined operatingscenarios of the wireless communication device 100. For example, thepredicted switching delays may differ in scenarios such as duringstartup of the wireless communication device 100, during normaloperation of the wireless communication device 100, during high power orlow power consumption of the wireless communication device 100 (or anyother power consumption mode as determined by comparison of currentpower consumption against one or more power thresholds), or during anyother pre-defined operating scenarios. In some implementations, thenominal control parameters 166 may be stored in a One Time Programmable(OTP) memory, with the nominal control parameters 166 determined, e.g.,during a factory calibration process.

Further embodiments describing the operation of the power transmittingunit 156 and the power receiving unit 155, including numerous optionalfunctions and features, are presented in conjunction with FIGS. 2-10that follow.

FIG. 2 is a schematic block diagram 200 of an embodiment of componentsof a wireless charging system. As just one example, the rectifiercircuit 210 may harvest 6.78 MHz Alliance for Wireless Power (A4WP)power transmissions. The rectifier circuit 210 facilitates efficiencyimprovements in receiving the transmitted energy and delivering it(e.g., as the rectified Direct Current (DC) voltage Vrect) to subsequentenergy consuming stages in the device, such as a battery chargingcircuit 164 for the battery 101.

Wireless power transmission suffers from efficiency losses at severalstages, e.g., from converting a power source into a radio frequency (RF)wireless power signal transmission, receiving the RF flux of thewireless power signal, and converting the RF flux into a usable DCvoltage in the receiving device. The wireless power receiver 158 employsmagnetic resonance achieved through matching the inductance 202 andcapacitance 204 and 206 to the transmitter system to obtain a high Qreceiver that is very responsive to the fundamental frequency (e.g.,6.78 MHz) of the wireless power signal.

In that regard, the inductance 202 may be a coil that receives the fluxof the wireless power signal. The inductance 202 may be, for example,one or more turns of a conductor on a printed circuit board, or anothertype of antenna. The inductance 202 produces an Alternating Current (AC)current and the capacitance 204 and 206 are tuned with respect to theinductance 202 to achieve the resonance that results in substantialresponsiveness to the wireless power signal. The wireless power receiver158 provides the AC current into the rectifier circuit 210, representedin FIG. 2 as a wireless power signal input 208 such as an AC currentsignal represented by AC Positive (ACP)/AC Negative (ACN).

The rectifier circuit 210 operates under control of the rectifiercontrol circuit 220 to convert the AC current into the DC voltage,Vrect. In one implementation, the rectifier circuit 210 and rectifiercontrol circuit 220 are integrated into an integrated circuit chip,though in other implementations discrete components may be used. Therectifier circuit 210 includes switching circuits (e.g., switchingcircuits 212, 214, 216, and 218) arranged to rectify the wireless powerinput signal to provide a wireless power output signal 162. Theswitching circuits 212, 214, 216, and 218 may be Metal OxideSemiconductor FETs (MOSFETs), for example, or other types of transistorsor other types of switches.

FIG. 2 shows diodes associated with each of the switching circuits 212,214, 216, and 218 such as body diodes associated with FETimplementations of these switching circuits. The body diodes may haverelatively poor conductivity, such that even if the FETs turn on afterthe body diodes become conductive, the body diodes do not significantlyaffect the impedance tuning of the rectifier circuit 210. In otherimplementations, switches without body diodes may be used. For example aFET switching structure including cascode connected transistors mayimplement the switches.

Rectifier control circuit 220 controls the switching circuits 212, 214,216, and 218 using switch control signals 238, 240, 242, and 244 togenerate a wireless power output signal 162, Vrect, as a full waverectified version of the wireless power input signal 208 that isfiltered by capacitor 250 into a substantially constant DC voltage—e.g.a DC voltage with acceptable variations or ripple. The switch controlsignals 238, 240, 242, and 244 include a switch-on signal and aswitch-off signal to individually control the ON and OFF states of eachof the switching circuits to provide efficient rectification.

Traditional rectifier control circuitry that operates at highfrequencies (above 1 MHz) requires the use of high bandwidth/lowpropagation delay comparators to sense when to turn on and off the powerFETs in the H-bridge. These high bandwidth/low propagation delaycomparators require high quiescent current to achieve the requiredspecifications for bandwidth and propagation delay. This high quiescentcurrent results in very poor low-load efficiency for the rectificationstage. Poor low load efficiency is particularly problematic in mobile orwearable devices where the power loss due to the rectification overheadcan become comparable to the load delivered to the system. The typicalcurrent for a comparator operating at 6.78 MHz for A4WP wireless poweris on the order of 1.5 mA thus, for 4 comparators, 6 mA of quiescentcurrent is required to sense when to turn on/off the FETs.

Further, precisely manipulating the turn on and turn off voltage for thesynchronous rectifier comparators relative to the ‘ideal’ switchingvoltage can provide some level of reactive tuning for the wireless powersystem. In general, it is difficult to generate precise turn-on andturn-off thresholds for the high bandwidth/low propagation delaycomparators without incurring speed or power penalties. In addition,High speed comparators are typically designed for zero-offset usingsmall devices for high bandwidth. Due to process and device mismatch,the threshold can vary +/−20-30 mV. This threshold variation results ininconsistent efficiency performance from device to device.

Wireless power systems are typically designed to operate at a fixed(A4WP) or slowly varying (WPC) frequency. Thus the delay time at whicheach comparator turns the power FETs on and off relative to ACP and ACNcrossing an arbitrary value is also fixed. Long term, as load powerincreases and decreases, delay timing will change but short term (overthe span of several carrier clock cycles) the timing remains relativelyconstant. Given this consistency, the rectifier control circuit 220 canpredict the switching delays and generate the switch control signalsbased on these predictions. In particular, high power comparators can beeliminated and replaced by a low power digital control loop thatpredicts the timing for turning on and off the FETs. For example thisdigital control loop can be designed to evaluate if the predicted timingdelays are too short or too long, and make the appropriate corrections.

FIG. 3 is a graphical diagram 300 of embodiments of switching waveforms.As discussed in conjunction with FIG. 2, the rectifier control circuit220 controls the switching circuits 212, 214, 216, and 218 using switchcontrol signals 238, 240, 242, and 244. The switching waveform 302 showsan ON threshold 304, labeled Von. As ACP rises toward Vrect, and passesthe ON threshold 304, the rectifier control circuit 220 may close theswitching circuits 214 and 218 to cause ACP to provide energy toward theoutput, Vrect. As ACP falls through the OFF threshold 306, Voff, (andACN is rising), the rectifier control circuit 220 may close theswitching circuits 212 and 216 to cause ACN to provide energy toward theoutput, Vrect.

In various embodiments, the rectifier control circuit 220 turns ON andOFF the switch 214 and 218 as a pair, and turn ON and OFF the switchingcircuits 212 and 216 as a pair. Doing so operates the rectifier circuit200 as a full wave rectifier. Turning switching circuits ON and OFF as apair can include turning the switching circuits ON and OFF atsubstantially the same time, or with comparison to substantially thesame reference voltages provided by the variable voltage sources.

In other implementations, however, the switch control signals 238, 240,242, and 244 may be set independently, and the switching circuits 212,214, 216, and 218 may thereby turn ON and OFF at independent times. Theswitching waveform 307 shows an ON tuning threshold 308 that rangesbetween Von-a and Von-b. The switching waveform 307 also shows an OFFtuning threshold 310 that ranges between Voff-a and Voff-b.

For example, rectifier control circuit can operate based on a thresholdvoltage, Vth, lower than Vrect, and, e.g., lower than any desiredswitching point. A delay circuit can be triggered at the point when ACPrises above Vth. In this way, a programmable delay time 322, Tdelay, maybe implemented to set the switch turn ON time to any selected time afterACP rises above Vth. While described in conjunction with a switch turnON time and ACP, further programmable delays can apply to a switch turnOFF time and further to switching based on ACN.

FIG. 4 is a schematic block diagram 400 of an embodiment of componentsof a wireless charging system. In particular, components of a powerreceiving unit, such as power receiving unit 155 are presented. Aspreviously discussed, the wireless power receiver 158 is configured toreceive a wireless power signal from a power transmitting unit. Acontrollable rectifier circuit 160 is configured to rectify the wirelesspower signal. The controllable rectifier circuit 160 includes arectifier circuit 210 that includes a plurality of switching circuitsconfigured to generate a rectified voltage, Vrect, from the wirelesspower signal, based on switch control signals 238, 240, 242 and 244 thatinclude a switch-on signal and a switch-off signal for correspondingones of the plurality of switching circuits. The rectifier controlcircuit 220 is configured to generate the switch control signals 238,240, 242 and 244 based on a prediction of switching delays.

In the embodiment shown, control feedback 222 is generated by feedbackgenerator 402 to aid the rectifier control circuit 220 in the predictionof switching delays used in generating the switch control signals 238,240, 242 and 244. The feedback generator 402 can be implemented via aprocessor 116 or other system logic 114. While shown as being separatefrom rectifier circuit 220, the functionality of rectifier controlcircuit 220 can nevertheless be combined into a single circuit,processor or other logic.

In various embodiments, while the rectifier control circuit 220 canitself predict switching delays, the control feedback 222 can includedesired voltage thresholds, initial switching delays, nominal controlparameters 166 and/or other prediction parameters that initialize and/oradapt the rectifier control circuit 220 to start-up conditions and otherpre-defined operating scenarios of the host device and/or provide otherfeedback to optimize or otherwise improve the performance of therectifier control circuit 220 in the prediction of switching delays usedin generating the switch control signals 238, 240, 242 and 244. Forexample, different switching timing may apply to startup of the wirelesscommunication device 100, during normal operation of the wirelesscommunication device 100, during high power or low power consumption ofthe wireless communication device 100 (or any other power consumptionmode as determined by comparison of current power consumption againstone or more power thresholds), or during any other pre-defined operatingscenarios. In some implementations, the nominal control parameters 166may be stored in a One Time Programmable (OTP) memory, with the nominalcontrol parameters 166 determined, e.g., during a factory calibrationprocess.

In addition, the control feedback 222 can include adjustments to voltagethresholds, switching delays and/or nominal control parameters 166 thatare generated based on feedback generated based on sampling theswitching waveforms 406 of one or more of the switching circuits. Inthis fashion, a voltage threshold used to trigger a timing delay thatsets a switch ON or switch OFF signal can be generated based on ameasured overshoot and/or a measured undershoot of the corresponding oneof the switching waveforms 406. In addition, samples of the alternatingcurrent draw by the wireless power receiver can be used to minimizecurrent draw or otherwise to optimize power factor, providing moreefficient power transfer. Further, sampling of current draw and/or therectified voltage over a plurality of cycles of the wireless powersignal can be further used to adjust voltage thresholds used in theprediction of switching delays to compensate for current conditions ingenerating the switch control signals 238, 240, 242 and 244.

For example, the feedback generator 402 can analyze the AC currentsignal ACP/ACN and generate control feedback 222 that is used to predictthe timing delays of the switching circuits 212, 214, 216 and 218. Moreparticularly, the feedback generator 402 provide control feedback 222 tothe rectifier control circuit 220 to generate switch control signals238, 240, 242 and 244 for efficient power transfer or other optimizationgoal. In that regard, the feedback generator 402 can measure andgenerate control feedback 222 in an attempt to reduce any phase shiftpresent between the AC current signal ACP/ACN and the ACP/ACN voltage.The control feedback 222 may provide control adjustments over timescales on the order of nanoseconds to microseconds, for instance, thoughfiner and coarser timing adjustments may also be made.

In another example, wireless communication device 100 can receive amessage specifying transmit power 404 (Ptx) over a communicationinterface (e.g., a Bluetooth interface or other control signaling)between the wireless communication device 100 and the power transmittingunit 156. The power receiving unit 155 can include a dedicated Bluetoothlow energy (BLE) interface, communicate with the power transmitting unit156 via load modulation or utilize one or more other communicationinterfaces of the wireless communication device 100 to provide such acontrol channel. The feedback generator 402 can measure the receivedpower (Prx), and compare the received power with the transmitted power(Ptx). The feedback generator 402 can then search, e.g., by adjustingcontrol feedback 222 and measuring the resulting effect on Prx, in anattempt to improve the timing delay predictions to maximize (as onepossible operational goal) the quantity Prx/Ptx.

In a further example, switching ON late (e.g., after ACP exceeds Vrect)allows ACP to rise faster. When the switching circuits turn ON, ACP isshorted through the switching circuits to Vrect. On the other hand,switching early (e.g. before ACP reaches Vrect) connects the highervoltage Vrect to ACP, and tends to slow the rise of ACP. Accordingly,the feedback generator 402 can adjust control feedback 222 to varyswitch timing predictions that affect when the switching circuits 212,214, 216 and 218 turn ON and OFF—impacting how fast ACP rises relativeto current actually flowing into Vrect. In this way, the feedbackgenerator 402 can implement changes in the current and voltage phaserelationship in an attempt to increase efficiency by keeping currentin-phase with voltage.

The feedback generator 402 can, as examples, implement open loopcontrol, closed loop control, or a combination of both. With open loopcontrol, the feedback generator 402 can, for instance, monitor the load,determine how much to change the switch timing, and implement thatchange. With closed loop control, for instance, the feedback generator402 can dither around the complex impedance that helps achieve thecurrent operational goal, e.g., for maximum power transfer tuning therectifier circuit 210 so that Vrect is maximized. The closed loopcontrol may thereby track to the complex impedance that best meets theoperational goal.

FIG. 5 is a graphical diagram 500 of an embodiment of switchingwaveforms. As discussed in conjunction with FIG. 4, the control feedback222 can include adjustments to voltage thresholds, switching delaysand/or nominal control parameters 166 that are generated based onfeedback generated based on sampling the switching waveform of one ormore of the switching circuits. In this fashion, a voltage thresholdused to trigger a timing delay that sets a switch ON or switch OFFsignal can be generated based a measured overshoot and/or a measuredundershoot of a corresponding one of the switching waveforms 406.

In particular, a desired response 542 of a switching waveform generatedby one of the switching circuits 212, 214, 216 or 218 is shown.Switching late can yield a switching waveform with overshoot544—indicating body diode conduction. In particular, switching too latecauses body diode conduction which results in power dissipated in thediode instead of the load reducing efficiency. Conversely, switchingearly can generate a switching waveform with undershoot 546—indicatingreverse current flow. In particular, switching too early results incurrent flowing from VRECT into the coil. This reverse current reducesefficiency as it requires the transmitter to overcome this reversecurrent before delivering charge into VRECT.

In various embodiments, the feedback generator 402 can sample theswitching waveform and measure the actual response curve to determinethe amount of undershoot and/or overshoot. In response, the feedbackgenerator can generate control feedback 222 to modify the switchingdelay predictions, increasing the timing delay in the event ofovershoot, and reducing the timing delay in the event of undershoot, inan attempt to generate a switching waveform with a desired response 542.While the undershoot and overshoot are shown in conjunction with theleading edge of the switching waveform, similar artifacts (notspecifically shown) can occur on the trailing edge of the switchingwaveform. Because the overshoot and undershoot occur in conjunction withthe leading edge and trailing edge of the switching waveform, samples ofthe switching waveforms can be limited to one or both of these regions.

FIG. 6 is a schematic block diagram 600 of an embodiment of componentsof a rectifier control circuit and a rectifier circuit. In particularcomponents of rectifier control circuit 220 and rectifier circuit 210are shown for a single switching circuit 666 that operates via ACP. Theother ACP switching circuit and the two ACN switching circuits canlikewise be implemented in a similar fashion. In the embodiment shown,the boundary between components of the rectifier circuit 210 and therectifier control circuit 220 is indicated by a dashed line.

The rectifier control circuit 220 includes a trigger circuit 606configured to generate a trigger signal 605 that indicates a point intime that the wireless power signal ACP crosses a first voltagethreshold (VTH). An adjustable delay line 620 includes a tapped delayline 618, multiplexers 608 and 612 and counters 610 and 614. The tappeddelay line 618 is clocked by delay clock generator 602 that includes aphase locked loop (PLL) and a string of delay elements. In anembodiment, the PLL operates on a 250 MHz reference frequency fref, soas to generate a delay control voltage 604 that sets replica 1 nsecdelay elements in delay lines 620 and 618—while consuming only a few uAof current. The adjustable delay line 620 is configured to generate theswitch-on signal 642 and switch-off signal 644 for the switchingcircuits based on predicted switching delays. The threshold VTH can benominally set at some value between VRECT and GND—a value low enough toinsure that the adjustable delay line is triggered prior to any possibleswitching point.

In operation, the trigger signal 605 initiates timing by the adjustabledelay line 620. The trigger signal 605 propagates down the tapped delayline 618 at 1 nsec intervals. The multiplexers 608 and 612 operate undercontrol of the up-down counters 610 and 614 to select the particulartiming delays (Tdelay) for the switch-on signal 642 and switch offsignal 644. These timing delays are predicted from the last cycle basedon the clocked comparators 622 and 624. The clocked comparators 622 and624 each include a sample and hold circuit to hold the comparison fromthe last cycle for use in timing of the next cycle. The clockedcomparator 622 is clocked by the switch-on signal 642 to compare thedivided rectifier signal (Vrect DIV) generated by divider 632 to adivided version of ACP (ACP_DIV) as adjusted by second voltage threshold(VTH_adj) set by threshold adjust 630 to generate a clocked comparison626. In particular, before the FET turns on, the clocked comparator 622is used to determine if ACP is above or below VRECT (as adjusted byVTH_adj). This comparison is used to increment or decrement the counter610 which adjusts the predicted switching delay by advancing orretarding the tap of the tapped delay line 618 selected by themultiplexer 608. In particular, the tap can be advanced if the clockedcomparison 626 indicates that the switch on timing is late and the tapcan be advanced if the clocked comparison 626 indicates that the switchon timing is early. As previously discussed, control feedback 222 can beused to set the value of VTH_adj, to provide further upward or downwardadjustment to the prediction based on other factors.

In a similar fashion, the clocked comparator 624 is clocked by theswitch-off signal 644 to compare the divided rectifier signal (VrectDIV) generated by divider 632 to a divided version of ACP (ACP_DIV) asadjusted by second voltage threshold (VTH_adj) set by threshold adjust630 to generate a clocked comparison 628. In particular, before the FETturns off, the clocked comparator 624 is used to determine if ACP isabove or below VRECT (as adjusted by VTH_adj). This comparison is usedto increment or decrement the counter 614 which adjusts the predictedswitching delay by advancing or retarding the tap of the tapped delayline 618 selected by the multiplexer 612. In particular, the tap can beadvanced if the clocked comparison 628 indicates that the switch offtiming is late and the tap can be advanced if the clocked comparison 628indicates that the switch off timing is early. As previously discussed,control feedback 222 can be used to set the value of VTH_adj, to providefurther upward or downward adjustment to the prediction based on otherfactors. It should be noted that while a single value VTH_adj, is shownas being used in the control of both the switch-on signal 642 and theswitch-off signal 644, separate values indicated by control feedback 222could be used for this purpose.

In various embodiments, the components of the rectifier circuit 210 areimplemented in a 24V domain while the components of the rectifiercontrol circuit 220 are implemented in a 1.5V domain, however, othervoltage domains could likewise be implemented. The switch-on signal 642and switch-off signal 644 are fed to D flip-flop 640. The output of theflip-flop 640 is level shifted to the 24V domain via level shift 660,and used by current driver 662 to switch on and off the FET 664.

This architecture eliminates the high current comparators that couldconsume 6 mA of quiescent current. In its place are the digital replicacells in a tapped delay line, a PLL, and mux circuits which can operateon the 1.5V core supply. The decision comparators can use a sample andhold front end and would have the entire 6.78 MHz cycle to make adecision so they can be designed for very low current as well. Theentire system can operate on the core 1.5V supply and consume, forexample, only a few hundred uA of quiescent current.

This architecture also addresses the difficulty in generating preciseturn-on and turn-off thresholds because it allows (via the dividers) amethod of adjusting the setpoint for the comparator to trip. Inaddition, this implementation also addresses the problem of part-to-partvariations. The clocked comparators 622 and 624 have the entire 6.78 MHzswitching cycle to make a decision. This allows the use of a lowbandwidth front end that uses large devices for low offset thussuppressing the part-to part variation. The architecture describedherein can be implemented in a smaller area with reduced currentconsumption compared with traditional designs. This architecture alsoimproves low-load rectification efficiency due to the reduced quiescentcurrent and allows for finer adjustment of rectifier FET switchingthresholds for reactive tuning and higher power transfer efficiency,faster charge times and higher charging before reaching a thermal limit.

FIG. 7 is schematic block diagrams 700 of embodiments of adjustablevoltage generators. In particular, several alternatives for thethreshold adjust 630 are shown. For example, an analog multiplexer 712,responsive to a voltage selection input such as VTH_adj, may performadjustment of ACP_DIV. As another example, the control logic may providea digital control bits (as a voltage selection input such as VTH_adj) toa Digital to Analog Converter (DAC) 714. The DAC 714 may then generatemultiple different voltages, as chosen by the control logic. As yetanother example, the control logic may adjust a programmable currentsource 716 using a voltage selection input such as VTH_adj to increaseor decrease current flowing through a reference resistor 718. Theincrease or decrease in current results in a change in the variablevoltage provided to the rectifier control circuit 220.

FIG. 8 is a schematic block diagram 800 of an embodiment of a powertransmitting unit and a power receiving unit. In particular, PTU 156includes a transmit resonator 812, matching circuit 802, power amplifier804 power supply 806, processing device 808 and wireless radio unit(WRU) 810. Wireless charging circuit 840 includes a wireless powerreceiver 158, a controllable rectifier circuit 160, a charging circuit164, a battery 101 and a processing device 828 that can include theoperation of feedback generator 402 and provide further control of thecharging circuit 164 for charging the battery 101. In addition, wirelesscharging circuit 840 includes a WRU 845 that communicates with the WRU810 for providing a control channel with the PTU 156.

In operation, the wireless charging circuit 840 receives a wirelesspower signal from PTU 156 to charge the battery 101 under control of theprocessing device 828. The WRU 845 also operates under control of theprocessing device 828 to establish a wireless connection with the WRU810 of PTU 156 via a connection establishment procedure. The WRU 845exchanges control data with the power transmitting unit 156 via thewireless connection to establish a charging session and/or to shareother control data and signaling. Processing device 808 controls theoperation of power supply 806 and power amplifier 804 to generate an RFpower signal. The matching circuit 802 couples the RF power signal tothe transmit resonator 812 for transmission. The RF power signal isreceived by the wireless power receiver 158, rectified by controllablerectifier circuit 160 and converted into a DC charging signal bycharging circuit 164 for charging of the battery 101. Processing device828 monitors and controls the charging to, for example, provide thefunctionality of feedback generator 402, avoid over-voltage andunder-voltage conditions, high temperature events, and/or otherdetrimental conditions.

The WRU 845 can receive a message specifying transmit power 404 (Ptx)from the WRU 845 of the power transmitting unit 156. The processingdevice 828 can measure the received power (Prx), and compare thereceived power with the transmitted power (Ptx). The processing device828 can then search, e.g., by adjusting control feedback 222 andmeasuring the resulting affect on Prx, in an attempt to maximize (as onepossible operational goal) the quantity Prx/Ptx.

The control channel between the WRU 845 and WRU 810 can be used toexchange other control data as well that can be used to increase deviceefficiency, power transfer and support other functions. In particular,the control channel can be used to communicate control data with thepower transmitting unit such as a battery status indication, a batteryvoltage, a voltage delta, a load condition, or a predicted change inload conditions. The power transmitting unit 156 can adjust a parameterof the transmitted wireless power signal in response to the controldata. The wireless charging circuit 840 can similarly receive controldata from the power transmitting unit 156 such as a voltage limit, acurrent limit, a power limit, a transient behavior parameter, a timingparameter, etc. The wireless charging circuit 840 can adjust a load orcharging parameter in response to the control data.

Too high a voltage delta between Vrect and the voltage of battery 101can waste power. The processing device 828 can sample the actual voltageof battery 101 and/or the voltage delta at the wireless charging circuit840 and the control channel can be used to provide control data to thePTU 156 that indicates the actual battery voltage and/or the voltagedata. This allows the PTU 156 to operate via processing device 808 tocontrol the transmit power to maintain an optimal voltage delta. Inparticular, the processor 808 of the PTU 156 can step-up or step downits output power via control of power supply 806 and/or power amplifier804 to react to changes in power needs and/or reduce the chance ofover-voltage or under-voltage conditions.

In a further example, control data from wireless charging circuit 840regarding the current loading and device state can be used to set adesired voltage delta and/or a desired power output. When the wirelesscharging circuit 840 is merely charging a lithium ion battery of thedevice at 3.3 volts, a small voltage delta of approximately 0.3 voltsmay be sufficient—with a desired Vrect of 3.6 volts. If however, anapplication processor is running higher current from a 5 volt powerrail, a higher voltage delta of approximately 1.0 volts may beneeded—with a desired Vrect of 6 volts. Again, the processor 808 of thePTU 156 can step-up or step down its output power via control of powersupply 806 and/or power amplifier 804 to react to changes in power needsand/or reduce the chance of over-voltage or under-voltage conditions.

In addition or in the alternative, the particular battery state can beshared via the control channel between the WRU 845 and WRU 810. In thisfashion, the processor 808 of the PTU 156 can adjust its output powervia control of power supply 806 and/or power amplifier 804 based onwhether the battery is currently in standby mode, constant voltage modeor constant current mode.

In addition to sharing information on current conditions, the processingdevice 828 can generate predicted load line data that is shared with thePTU 156 in order to maximize power transfer. For example, the processingdevice 828 can monitor device state and activities and alert the PTU 156when its load is about to increase due to a planned increase inprocessor speed of the host device, a plan to transmit by the hostdevice, a plan to turn on additional devices, and/or a decrease in loaddue to a suspension of any of these activities. The step response of thePTU 156 to changes in output power level may not be instantaneous andconsequently have an associated delay until the transmit power settleson a desired steady state level. In response this this information fromthe wireless charging circuit 840, the processor 808 of the PTU 156 canbegin to step-up or step down its output power via control of powersupply 806 and/or power amplifier 804 to anticipate changes in powerneeds, reducing the chance of over-voltage or under-voltage conditionsand being better able to confirm to changes in steady state powerdemands from the wireless charging circuit 840.

In yet another example, the processing device 828 operates to controlits loading/current usage, based on transmitter characteristics andpower transfer either provided via the control channel from the PTU 156or based on measurements of received power via the processing device.For example, the PTU 156 can share voltage, current or other powerlimits, transient behavior parameters, timing information, etc. Forexample, the processing device 828 can operate to limit loading in casesof power delivery transients, determine a level of steady state powersurplus and allocate that power surplus charging. In a similar fashion,the processing device 828 can provide input to the host device toregulate the consumed power to maintain a predetermined rate of batterycharging or otherwise to maintain the rate of battery charging below therate of power being received by the wireless charging circuit 840.

While the foregoing has described the implementation of a controlchannel between the PTU 156 and the wireless charging circuit 840 thatoperates via WRUs 810 and 845, other control channels implemented viaload modulation or alternative wireless links can likewise beimplemented.

FIG. 9 is a flowchart representation 900 of an embodiment of a method.In particular, a method is presented for use with one or more functionsand features described in conjunction with FIGS. 1-8. Step 902 includesreceiving a wireless power signal from a power transmitting unit. Step904 includes generating a rectified voltage from the wireless powersignal in a power receiving unit, based on switch control signals thatinclude a switch-on signal and a switch-off signal for correspondingones of the plurality of switching circuits. Step 906 includes adjustingpredicted switch delays. Step 908 includes generating the switch controlsignals based on the predicted switching delays.

FIG. 10 is a flowchart representation 1000 of an embodiment of a method.In an acquisition mode of operation, the system logic 114, viaprocessing device 828 or circuit or device may determine an acquisitionoperating goal (step 1002), as examples maximum power transfer, powerfactor, undershoot, overshoot, or power transfer to Vrect above apre-determined threshold amount, etc. In acquisition mode, the systemlogic 114 may sweep switching delays, e.g., over a pre-define delayrange at, e.g., pre-defined delay increments for any particular switchor combination of switches in the controllable rectifier circuit 160(step 1004). At each set of switching delays presently implemented, thesystem logic 114 may measure circuit parameters for a given length oftime (step 1006), e.g., a specified number of clock cycles, or aspecified duration. Examples of circuit parameters include the currentand voltage phase of ACP/ACN, the magnitude of Vrect, the compleximpedance presented by the switching circuit, and other parameters thatbear upon the current operating goal. The system logic 114 therebylocates the switching delays that help achieve the current operatinggoal (step 1008) as informed by the measured circuit parameters. Forinstance, for maximizing power transfer, the sweep may find theswitching delay for each switch over the measurement period at whichVrect is largest, overshoot and overshoot are lowest, current draw islowest, on average. The switching delays that achieve the acquisitionoperating goal may be saved, e.g., in the memory 120, for use as asubsequent starting point, or for any other future use as, for examplenominal control parameters 166 (step 1010).

After acquisition mode, the system logic 114 may transition to anoperational mode that has the same or different operational goal asacquisition mode (step 1012). The current operating goal may change atany time. In operational mode, the system logic 114 may, duringoperation of the controllable rectifier circuit 160, explore around thecurrent operating point (e.g., by dithering around previously setswitching delays via adjustments to control feedback 222) (step 1014).The exploration may facilitate tracking to the switching delays thathelp accomplish the current operating goal, e.g., as the load changes(step 1016). The control feedback 222 that help accomplish anyparticular operating goal may be saved for future reference, e.g., inthe memory 120 (step 1018). There may be a library of control feedback222 established in the device for use in predicting switching delays toimplement for any particular operating goal.

In one implementation, the exploration may start with control feedback222 that yield switching delays at one extreme, e.g., the shortestswitching delays. The exploration may then increase the delays and walkup the result curve for the current operating goal (e.g., maximum powertransfer), until the set of parameters is reached where the resultbegins to fall off. That set of parameters may become the currentoperating point. The exploration may then search around the currentoperating point to facilitate tracking toward the current operating goalin the face of, e.g., load or other changes.

As noted above, in some implementations, when the host device is apredetermined operating mode, e.g., starting up, booting, or is anotherpredetermined a state, the system logic may set the switching delays toa startup set of delays. The startup set of delays may be obtained fromthe nominal tuning parameters 166 in the memory 120, or form othersource (e.g., the PTU 156 over a communication like, such as a Bluetoothlink). Typically, prior to nominal operation, power consumption is muchlower, and the switching delays that provide a desired amount of powertransfer via Vrect are more broadband in nature in that a wider range ofdelays will obtain the desired power transfer. As a result, the hostdevice may receive sufficient power during bootup to provide power forsubsequent system operation, and perform tracking to help meet thecurrent operational goal, e.g., maximum power transfer.

As power consumption increases, the load increases, and the load on thewireless power receiver 158 increases. The impedance of the load willhave significant effects on power transfer and efficiency. According,the system logic 114 may measure circuit parameters such as switchingwaveform voltages, current draw and/or other parameters during operationin order to dynamically tune the control feedback to yield switchingdelays that continue to track the current desired operational goal.

As may also be used herein, the term(s) “operably coupled to”, “coupledto”, and/or “coupling” includes direct coupling between items and/orindirect coupling between items via an intervening item (e.g., an itemincludes, but is not limited to, a component, an element, a circuit,and/or a module) where, for indirect coupling, the intervening item doesnot modify the information of a signal but may adjust its current level,voltage level, and/or power level. As may further be used herein,inferred coupling (i.e., where one element is coupled to another elementby inference) includes direct and indirect coupling between two items inthe same manner as “coupled to”. As may even further be used herein, theterm “operable to” or “operably coupled to” indicates that an itemincludes one or more of power connections, input(s), output(s), etc., toperform, when activated, one or more its corresponding functions and mayfurther include inferred coupling to one or more other items. As maystill further be used herein, the term “associated with”, includesdirect and/or indirect coupling of separate items and/or one item beingembedded within another item.

As may also be used herein, the terms “processing module”, “module”,“processing circuit”, and/or “processing unit” (e.g., including variousmodules and/or circuitries such as may be operative, implemented, and/orfor encoding, for decoding, for baseband processing, etc.) may be asingle processing device or a plurality of processing devices. Such aprocessing device may be a microprocessor, micro-controller, digitalsignal processor, microcomputer, central processing unit, fieldprogrammable gate array, programmable logic device, state machine, logiccircuitry, analog circuitry, digital circuitry, and/or any device thatmanipulates signals (analog and/or digital) based on hard coding of thecircuitry and/or operational instructions. The processing module,module, processing circuit, and/or processing unit may have anassociated memory and/or an integrated memory element, which may be asingle memory device, a plurality of memory devices, and/or embeddedcircuitry of the processing module, module, processing circuit, and/orprocessing unit. Such a memory device may be a read-only memory (ROM),random access memory (RAM), volatile memory, non-volatile memory, staticmemory, dynamic memory, flash memory, cache memory, and/or any devicethat stores digital information. Note that if the processing module,module, processing circuit, and/or processing unit includes more thanone processing device, the processing devices may be centrally located(e.g., directly coupled together via a wired and/or wireless busstructure) or may be distributedly located (e.g., cloud computing viaindirect coupling via a local area network and/or a wide area network).Further note that if the processing module, module, processing circuit,and/or processing unit implements one or more of its functions via astate machine, analog circuitry, digital circuitry, and/or logiccircuitry, the memory and/or memory element storing the correspondingoperational instructions may be embedded within, or external to, thecircuitry comprising the state machine, analog circuitry, digitalcircuitry, and/or logic circuitry. Still further note that, the memoryelement may store, and the processing module, module, processingcircuit, and/or processing unit executes, hard coded and/or operationalinstructions corresponding to at least some of the steps and/orfunctions illustrated in one or more of the Figures. Such a memorydevice or memory element can be included in an article of manufacture.

Various embodiments have been described above with the aid of methodsteps illustrating the performance of specified functions andrelationships thereof. The boundaries and sequence of these functionalbuilding blocks and method steps have been arbitrarily defined hereinfor convenience of description. Alternate boundaries and sequences canbe defined so long as the specified functions and relationships areappropriately performed. Any such alternate boundaries or sequences arethus within the scope and spirit of the claims. Further, the boundariesof these functional building blocks have been arbitrarily defined forconvenience of description. Alternate boundaries could be defined aslong as the certain significant functions are appropriately performed.Similarly, flow diagram blocks may also have been arbitrarily definedherein to illustrate certain significant functionality. To the extentused, the flow diagram block boundaries and sequence could have beendefined otherwise and still perform the certain significantfunctionality. Such alternate definitions of both functional buildingblocks and flow diagram blocks and sequences are thus within the scopeand spirit of the claims. One of average skill in the art will alsorecognize that the functional building blocks, and other illustrativeblocks, modules and components herein, can be implemented as illustratedor by discrete components, application specific integrated circuits,processors executing appropriate software and the like or anycombination thereof.

A physical embodiment of an apparatus, an article of manufacture, amachine, and/or of a process that includes one or more embodiments mayinclude one or more of the aspects, features, concepts, examples, etc.described with herein. Further, from figure to figure, the embodimentsmay incorporate the same or similarly named functions, steps, modules,etc. that may use the same or different reference numbers and, as such,the functions, steps, modules, etc. may be the same or similarfunctions, steps, modules, etc. or different ones.

The term “module” is used in the description of the various. A moduleincludes a functional block that is implemented via hardware to performone or module functions such as the processing of one or more inputsignals to produce one or more output signals. The hardware thatimplements the module may itself operate in conjunction software, and/orfirmware. As used herein, a module may contain one or more sub-modulesthat themselves are modules.

While particular combinations of various options, methods, functions andfeatures have been expressly described herein, other combinations ofthese options, methods, functions and features are likewise possible.The various embodiments are not limited by the particular examplesdisclosed herein and expressly incorporates these other combinations.

What is claimed is:
 1. A first apparatus comprising: a wireless powerreceiver configured to receive a wireless power signal from a secondapparatus; a rectifier circuit configured to rectify the wireless powersignal to generate a rectified power signal to charge a battery; and afirst wireless radio configured to communicate control data using asecond wireless radio of the second apparatus via a wireless channelbetween the first apparatus and the second apparatus, the control datato control the wireless power signal between the first apparatus and thesecond apparatus, wherein the control data comprises an indication oftransmitted power of the wireless power signal from the secondapparatus, wherein the indication of the transmitted power istransmitted from the second apparatus to the first apparatus.
 2. Thefirst apparatus of claim 1, wherein the control data includes anindication of a predicted change of load conditions, wherein theindication of the predicted change of load conditions is transmittedfrom the first wireless radio of the first apparatus to the secondwireless radio of the second apparatus via the wireless channel.
 3. Thefirst apparatus of claim 1, wherein the indication of the transmittedpower is transmitted from the second wireless radio of the secondapparatus to the first wireless radio of the first apparatus via thewireless channel.
 4. The first apparatus of claim 1, wherein the controldata includes battery state data transmitted from the second wirelessradio of the second apparatus to the first wireless radio of the firstapparatus via the wireless channel, wherein the battery state dataincludes one of: a standby mode, constant voltage mode or constantcurrent mode.
 5. The first apparatus of claim 1, wherein the controldata includes charging status data transmitted from the first wirelessradio of the first apparatus to the second wireless radio of the secondapparatus via the wireless channel, wherein the charging status dataincludes at least one of: a battery status indication, a batteryvoltage, voltage delta or a load condition, and wherein the secondapparatus adjusts a parameter of the wireless power signal in responseto the charging status data.
 6. The first apparatus of claim 1, whereinthe control data includes battery voltage data transmitted from thefirst wireless radio of the first apparatus to the second wireless radioof the second apparatus via the wireless channel, and wherein the secondapparatus adjusts the wireless power signal, based on the batteryvoltage data.
 7. The first apparatus of claim 1, wherein the controldata includes power generation data transmitted from the first wirelessradio of the first apparatus to the second wireless radio of the secondapparatus via the wireless channel, wherein the power generation dataincludes at least one of: a voltage limit, a current limit, a powerlimit, a transient behavior parameter or a timing parameter.
 8. Thefirst apparatus of claim 1, wherein the control data includes batterystate data transmitted from the first wireless radio of the firstapparatus to the second wireless radio of the second apparatus via thewireless channel, wherein the battery state data includes one of: astandby mode, constant voltage mode or constant current mode.
 9. Thefirst apparatus of claim 1, wherein the control data includes predictedload line data transmitted from the first wireless radio of the firstapparatus to the second wireless radio of the second apparatus via thewireless channel, wherein the predicted load line data indicates aplanned change in a load of a host device that contains the firstapparatus.
 10. The first apparatus of claim 9, wherein the plannedchange in the load of the host device includes one of: a plannedincrease in the load of the host device or a planned decrease in theload of the host device.
 11. A first apparatus comprising: a firstwireless radio configured to communicate control data using a secondwireless radio of a second apparatus via a wireless channel between thefirst apparatus and the second apparatus, the control data to control awireless power signal between the first apparatus and the secondapparatus; a processing circuit configured to determine transmit poweraccording to the control data; and a wireless power transmitterconfigured to transmit the wireless power signal to the second apparatusaccording to the determined transmit power, wherein the control datacomprises battery state data transmitted from the second wireless radioof the second apparatus to the first wireless radio of the firstapparatus via the wireless channel, wherein the battery state datacomprises one of: a standby mode, constant voltage mode or constantcurrent mode.
 12. The first apparatus of claim 11, wherein the controldata includes an indication of a predicted change of load conditions,wherein the indication of the predicted change of load conditions istransmitted from the second wireless radio of the second apparatus tothe first wireless radio of the first apparatus via the wirelesschannel.
 13. The first apparatus of claim 11, wherein the control dataincludes an indication of transmitted power of the wireless power signalfrom the first apparatus, wherein the indication of the transmittedpower is transmitted from the first wireless radio of the firstapparatus to the second wireless radio of the second apparatus via thewireless channel.
 14. The first apparatus of claim 11, wherein thecontrol data includes charging status data transmitted from the secondwireless radio of the second apparatus to the first wireless radio ofthe first apparatus via the wireless channel, wherein the chargingstatus data includes at least one of: a battery status indication, abattery voltage, voltage delta or a load condition, and wherein thefirst apparatus adjusts a parameter of the wireless power signal inresponse to the charging status data.
 15. The first apparatus of claim11, wherein the control data includes battery voltage data transmittedfrom the second wireless radio of the second apparatus to the firstwireless radio of the first apparatus via the wireless channel, andwherein the processing circuit adjusts the wireless power signal, basedon the battery voltage data.
 16. The first apparatus of claim 11,wherein the control data includes power generation data transmitted fromthe second wireless radio of the second apparatus to the first wirelessradio of the first apparatus via the wireless channel, wherein the powergeneration data includes at least one of: a voltage limit, a currentlimit, a power limit, a transient behavior parameter or a timingparameter.
 17. A first apparatus comprising: a wireless power receiverconfigured to receive a wireless power signal from a second apparatus; arectifier circuit configured to rectify the wireless power signal togenerate a rectified power signal to charge a battery; a first wirelessradio configured to exchange control data with a second wireless radioof the second apparatus via a wireless channel, the control data tocontrol the wireless power signal between the first apparatus and thesecond apparatus; and a processing circuit, coupled to the firstwireless radio and the rectifier circuit, wherein the processing circuitdetermines a received power corresponding to the wireless power signaland controls the rectifier circuit to adjust a ratio of the receivedpower to the transmitted power, wherein the control data includes anindication of transmitted power of the wireless power signal from thesecond apparatus, wherein the indication of the transmitted power istransmitted from the second wireless radio of the second apparatus tothe first wireless radio of the first apparatus via the wirelesschannel.
 18. A method comprising: receiving by a first apparatus,control data from a second apparatus via a wireless channel, the controldata to control a wireless power signal between the first apparatus andthe second apparatus; determining, by the first apparatus, transmitpower according to the control data; transmitting, by the firstapparatus to the second apparatus via the wireless channel, anindication of the transmit power; and transmitting, by the firstapparatus, the wireless power signal to the second apparatus accordingto the determined transmit power.
 19. A method comprising: receiving bya first apparatus, control data from a second apparatus via a wirelesschannel, the control data to control a wireless power signal between thefirst apparatus and the second apparatus; determining, by the firstapparatus, transmit power according to the control data; transmitting,by the first apparatus, the wireless power signal to the secondapparatus according to the determined transmit power; and receiving, bythe first apparatus from the second apparatus via the wireless channel,the control data including an indication of a predicted change of loadconditions.
 20. The method of claim 18, further comprising: determininga received power corresponding to the wireless power signal andcontrolling the second apparatus to adjust a ratio of the received powerto the transmitted power.